How long do you need to work in the marketing field before you get involved in the management side of marketing?

i think it's irrelevant, maybe i have the experience, but i don't have the management skills, or i have the management skills but i do not have the experience.
what i am believe is: if you have the market sense from different angle, and know your customer, your value, and the best way to deliver the value, in the right time and right place, in addition you have the management skills, then you are qualified for getting involved in the management side of marketing.

Whenever you know how to manage people, time, cost you will be ready, and you will feel your self in the right track whenever you can be responsible for others mistakes not only yours :)

I would say it requires about 5 years experience in the field before moving into management side of marketing.
This time frame gives amble opportunities to test your ideas, experience the results and correct yourself.
This will help you make better decisions in future, which would be received well by your subordinates as well.

this question reminds me with what the God father of the marketing Philip kotler said :- ( its takes one hour to learn the marketing principle and its take the lifetime to master the marketing)

i think at least 5 years to get good experience

Minimum 2 years.